Plant propagating block



FIG. 1 is an enlarged isometric view of a plant propagating block showing my new design;

FIG. 2 is an end view;

FIG. 3 is a front view, the rear view being identical;

FIG. 4 is a top view; and

FIG. 5 is a bottom view. 

The ornamental design for a plant propagating block, as shown. 